1. Field of the Invention
This invention relates to a measurement device and a measuring method, more particularly to a measurement device that uses a cuff to measure blood pressure.
2. Description of the Related Art
Based on the nature of a disease, there are cases where it is necessary to capture blood pressure variations of a long period of time, for example, of a circadian pattern and the like. In order to know blood pressure variations, a way of use is known where a measurement device is mounted and blood pressure measurements are performed at predetermined intervals over a long period. Further, there is also a need of desiring to also capture, along with a blood pressure value in the period of time, a variation in pulse in that period of time.
As a sphygmomanometer used to measure blood pressure variations in a long period of time, a wrist sphygmomanometer where a cuff is mounted on a wrist can reduce a burden on a patient over a type where the cuff is mounted on an upper arm. Furthermore, a wrist radial artery can be said to be a suitable area for pulse measurement because the artery is located in a place where a subcutaneous is shallower than the upper arm.
Then, using a wrist sphygmomanometer mounting a function to measure pulse as a device to measure blood pressure and pulse over a long period of time, it can be envisioned that the wrist sphygmomanometer measures pulse in a time period other than at the time of measuring blood pressure.
Here, a method of measuring pulse rate is known where a volume change of an artery in a location where the subcutaneous is relatively shallow is noninvasively detected as a method for measuring pulse. In particular, as measurement methods of simple configuration there are, 1) A method using a cuff that mildly compresses a wrist of the patient and detects variations in cuff pressure with a pressure sensor, and 2) A method that measures the volume change of the artery using a photoelectronic sensor or an impedance sensor mounted and arranged above the artery.
Whether in the case of measuring with the method of 1) or in the case of measuring with the method of 2) above, because a cuff is provided in the sphygmomanometer, use of the cuff is possible. That is, it can be envisioned that the cuff is used for the mild compression of the methods of 1) and 2) above and for attaching the sensors to skin of the method of 2).
Incidentally, the cuff used for blood pressure measurement is configured of an effective size to wrap around a measurement location in a circumferential direction. This size is regulated through, for example, the American Heart Association (AHA) and the like. When attempting to measure continuous pulse on timing other than at the time of measuring blood pressure using this kind of cuff, it is necessary to keep lightly compressing on the wrist of the patient over a long period of time with either the method of 1) or the method of 2) above. Because of that, a possibility increases that a venous flow of an entire circumference of the wrist will be blocked and blood stasis will occur. Also, by compressing the entire circumference of the wrist over a long period of time, the patient may be caused to feel a sense of restraint.